The present invention relates to lamp sockets for the series or parallel connection of electric lamps in a light string, and particularly to those receiving miniature screw-in type lamps operating at a low voltage.
Small and miniature lights are commonly used in decorative light strings and on various natural and artificial elements. Each light is configured as a socket and a lamp. The socket receives a portion of the lamp base of the lamp and makes electrical contact between the filament of the lamp and the electrical power lines.
Normally, a lamp with a bayonet base is inserted into the socket and makes contact with the outside power lines. For example, in U.S. Pat. No. 4,807,098, a lamp bulb with two filament leads are inserted in a circular socket, then the socket is pushed in a housing with contact plates which are connected with the outside electrical power lines. Alternatively, the lamp base is screwed into the socket by a rotational thread. A particular problem encountered with the push-in type lamp is that it easily loses electrical contact during use, as a result of accidental touching or vibration thereof. The screw-in type lamp may be better for secured connection but it causes other problems, such as high cost, difficulty in bonding the socket and housing and soldering the wires to outside lines.